During Britain’s first European referendum campaign in 1975 the In side vastly outspent the Outers — by 20 to one by some estimates. Even just taking the official campaigns — and there were many other pro-EEC groups — the Britain in Europe campaign declared spending of £1,481,583 (roughly £11.2 million in today’s money) while the National Referendum Campaign, the Out side, spent £133,630 (just over £1 million today). The NRC managed to raise only £8,610, apart from its government grant of £125,000.

Such extreme disparities of spending will not occur this year. During the referendum period — April 15 to June 23, the day of the vote — both official designated lead campaigns will be able to spend up to £7 million, receiving a government grant of £600,000. There are passionate wealthy supporters on both sides and neither campaign should have any difficulty in raising this amount. In addition, there can be any number of other registered campaigns on either side who can spend up to £700,000 each.

Nevertheless, the spending rules in place for this year’s referendum mean that the Remain campaign will have the capacity substantially to outspend the Leave side. Political parties which register as campaigners on either side have their own spending limits, depending on the percentage of the vote they obtained in the 2015 general election. Those that received more than 30 per cent of the vote (Conservatives and Labour) can spend up to £7 million; between 10 and 20 per cent (UKIP), £4 million; between 5 and 10 per cent (Lib Dems), £3 million; and those below 5 per cent, £700,000 (SNP, Plaid Cymru, Greens). The Tories have announced that as a party they are staying neutral and will not register as a campaigner, meaning that they will be able to spend no more than £10,000 on the referendum. The pro-membership parties, which they have a combined spending limit of £12.1 million, will be able to outspend the leavers (i.e. UKIP) by three to one.

To spend up to their limits the parties do, of course, need to have the funds available. The finances of Labour and the Lib Dems, and for that matter UKIP, are very far from rosy. There are few wealthy donors who wish to shell out money to Jeremy Corbyn’s Labour party and the big unions are very half-hearted in their support of the EU. Labour’s Remain campaign is, however, being run by the more agreeable Alan Johnson, not Corbyn, and past party donors such as staunch Europhile David Sainsbury will be much less reluctant to open their chequebooks for him. It seems likely that we are again looking at a referendum where the pro-membership side will outspend the outers.